UNIVERSITY  OF  CALIFORNIA. 

AGRICULTURAL  EXPERIMENT  STATION. 
BERKELEY,  CAL. 


E.  W.  HILGARD,  Director. 


BULLETIN  No.   116. 


Much  enlarged.     Length  one-tenth  inch. 

THE  CALIFORNIA  VINE  HOPPER. 

MAY,   1897. 


miii«iiniT-iiiniT-iimi  tmttmmi\t 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/californiavineho116wood 


THE  CALIFORNIA  VINE  HOPPER. 


By  C.  W.  Woodworth. 


Four  things  injuring  the  vineyards  in  this  State  may  be  counted  as  of 
the  first  importance  and  as  doing  the  greatest  amount  of  injury  They 
are  first,  the  mysterious  and  fatal  Anaheim  disease,  which  has  almost 
stricken  from  the  list  of  the  vine-growing  regions  of  this  State  a  large 
district  around  Anaheim  and  which  has  entirely  baffled  the  researches 
of  trained  investigators,  and  which  does  not  yield  to  any  known  method 
of  treatment.  Second,  the  Phylloxera,  which,  were  it  not  for  the  pro- 
tection available  by  the  use  of  resistant  roots,  would,  as  it  threatened  to 
do  in  Europe,  practically  annihilate  every  planting  of  European  vines. 
Third,  the  mildew,  which  is  capable  of  inflicting  an  immense  amount  of 
injury,  especially  in  the  moister  regions  where  the  production  of  fruit 
would  be  practically  impossible  if  we  did  not  know  and  use  the  proper 
remedy  :  sulphur.  Finally,  the  vine  hopper,  which  is  by  no  means  in- 
trinsically as  injurious  as  either  of  the  others,  but  because  of  its  pres- 
ence almost  everywhere,  and  the  absence  heretofore  of  a  remedy,  has 
probably  done  year  by  year  as  much  injury  as  any  of  the  others.  The 
Anaheim  disease  and  the  Phylloxera  threaten  the  very  life  of  the  vine, 
while  the  mildew  and  vine  hopper  decrease  the  crop  and  make  it  unpro- 
fitable, which  from  the  standpoint  of  the  farmer  is  equally  as  serious  a 
matter.  Mildew  does  its  greatest  injury  in  the  moister  regions  and  in 
the  spring  of  the  year,  while  the  vine  hopper  is  more  serious  in  the  drier 
regions  and  in  the  summer  and  fall. 

As  has  been  stated  above,  there  has  heretofore  been  no  remedy  found 
for  the  vine  hopper,  and  everything  that  has  been  tried  has  proven  use- 
less. The  object  of  this  article  is  to  point  out  the  reasons  for  the  failure 
of  these  attempts  at  treatment,  so  that  others  will  not  waste  money  in  a 
useless  line  of  experimentation,  and  to  suggest  a  line  of  work  giving 
much  more  promise  of  results  and  bidding  fair  to  be  a  solution  of  the 
problem.  It  will  at  least  be  useful  to  carefully  enumerate  and  discuss 
the  factors  in  the  problem,  for  the  solution  of  it  will  mean  hundreds  of 
thousands  of  dollars  to  the  farmers  of  the  State. 


There  are  many  important  facts  in  reference  to  this  insect  that  we  are 
still  unacquainted  with,  and  some  of  the  very  generally  accepted  ideas 
are  entirely  erroneous.  We  will  first  discuss  the  facts  in  the  life  history 
of  the  insect  and  its  relation  to  the  grape  vine,  and  then  consider  the 
remedies. 

THK   HOPPERS   IN   WINTER. 

This  is  a  point  in  the  life  history  about  which  there  is  the  greatest 
difference  of  opinion  among  farmers,  and  the  most  erroneous  ideas  exist. 
The  commonest  of  these  errors  we  will  enumerate  and  discuss. 

The  insect  does  not  pass  the  winter  as  an  egg.  In  the  spring  there  is 
no  such  a  thing  as  hatching  out.  Warm  weather  cannot  aid  nor  cold 
weather  retard  their  hatching,  because  they  do  not  hatch  at  that  time 
of  the  year.  The  insect  that  occurs  in  the  spring  is  not  a  young  insect. 
Everything  done  in  the  winter  with  the  idea  of  destroying  the  eggs  is 
done  on  a  wrong  theory,  for  there  are  no  eggs  to  destroy  at  that  time. 
A  great  deal  of  time  and  money  has  been  spent  every  year  in  acting  on 
this  erroneous  theory. 

The  i?isect  does  not  pass  the  winter  in  the  ground,  in  any  form,  at  least 
to  any  extent.  The  ground  would  be  the  last  place  to  look  in  the  winter 
for  living  leaf  hoppers.  The  idea  probably  arose  because  some  other 
common  insects,  with  an  entirely  different  life  history,  do  pass  the 
winter  in  the  ground  (the  grasshopper  for  instance,  in  the  form  of 
masses  of  eggs),  and  partly  because  dead  hoppers  can  often  be  seen  on 
the  ground  in  the  fall  in  considerable  numbers.  Whatever  is  done  in 
the  winter  to  the  soil  will  not  have  any  effect  on  the  hopper. 

The  insect  does  not  pass  the  winter  about  the  vine,  in  any  considerable 
numbers.  Some  suppose  the  bark  is  full  of  eggs  that  hatch  in  the 
spring,  and  others  think  the  insect  is  hiding  beneath  it.  Both  ideas  are 
entirely  wrong.  On  the  one  hand  no  eggs  pas's  the  winter,  and  on  the 
other  the  insects  could  be  found  if  they  were  actually  hiding  there  ;  but 
in  truth  only  an  occasional  one  can  be  seen.  Some  scale  insects  may  be 
killed  by  spraying  the  plant  in  the  winter,  but  the  vine  hopper  is  a  dif- 
ferent kind  of  insect  and  the  money  which  is  spent  every  winter,  some- 
where, experimenting  with  the  vine  hopper,  is  that  much  thrown  away. 

The  insect  does  not  pass  the  winter  in  the  fallen  leaves  to  any  great  ex- 
tent. This  is  the  most  wide-spread  idea  in  this  State  and  is  based,  not 
on  observation,  but  on  statements  in  books  which  refer  to  the  eastern 
insect  and  the  eastern  winter,  and  even  there  is  not  strictly  true  and  as 
regards  the  condition  here  is  absolutely  false.  A  good  many  hoppers 
may  be  found  on  the  fallen  leaves  in  the  fall,  but  they  do  not  pass  the 
winter  there  and  all  that  tr}^  to  do  so  die.  With  our  warm  winter  they 
must  have  food.  They  cannot  sleep  over  winter  as  they  could  if  it  were 
colder.  A  few  may  be  found  anywhere  in  the  winter  even  on  the  dead 
leaves,  but  they  cannot  stay  there  all  winter.  Much  money  has  been 
spent  every  winter  in  the  destruction  of  leaves,  and  those  that  have  tried 


— b— 

the  experiment  have  been  at  a  loss  to  know  why  they  produced  no  prac- 
tical results,  and  have  blamed  their  neighbors  for  not  doing  likewise, 
thinking  that  the  neighbors  harbored  the  insects  that  attacked  them  in 
the  spring. 

During  the  winter  the  insect  leads  a  somewhat  active  life,  feeding  on 
every  variety  of  plant  that  is  green.  They  may  be  found  anywhere  at 
any  time.  Every  insect  that  attacks  the  vine  in  the  spring  has  been 
present  in  the  neighborhood  of  that  vine  all  winter  as  an  adult  active 
insect. 

Winter  is  a  very  critical  time  in  the  history  of  these  insects.  In  the 
fall  they  may  be  found  of  all  ages  and  sizes,  from  the  egg  to  the  aged 
perfect  insect,  but  the  winter  climate  is  so  fatal  that  all  the  eggs  and 
young  die,  and  of  the  adults  only  the  youngest  and  most  vigorous  sur- 
vive. If  the  winter  is  more  than  usually  severe,  they  will  be  very  much 
reduced  in  numbers  and  do  but  little  injury,  and  that  late  in  the  season, 
when  they  will  have  increased  sufficiently  in  numbers.  But  if  on  the 
other  hand  the  winter  is  favorable  to  them,  as  the  past  winter  has  been, 
they  will  begin  in  large  numbers  and,  if  nothing  happens  to  check  them, 
may  do  very  great  damage. 

During  their  winter  life  the  insects,  though  somewhat  active,  are  by 
no  means  so  active  as  in  the  summer,  and  they  are  therefore  much  less 
conspicuous.  The  injury  they  do  to  plants  is  also  very  slight.  They 
only  take  enough  food  to  meet  their  present  needs  and  the  plants  they 
attack  generally  suffer  scarcely  at  all.  During  the  colder  weather  they 
are  especially  inactive  ;  many  fall  from  the  plants  and  lie  on  the  ground, 
and  are  quite  difficult  to  find. 

While  the  insects  feed  on  all  varieties  of  plants,  they  have  decided 
preferences  for  some,  and  will  be  found  much  more  abundantly  on  such 
plants.  Often  toward  spring  the  leaves  will  show  the  effects  of  their 
attacks  by  the  small  paler  spots  characteristic  of  the  work  of  insects  of 
this  group. 


THE    HOPPERS   IN   SPRING. 

With  the  coming  of  the  warmer  weather  in  the  spring,  the  needs  of 
the  insects  increase  not  only  on  account  of  the  more  active  life,  during 
warm  weather,  but  because  food  must  be  taken  with  which  to  produce 
their  eggs.  When  the  leaf  hoppers  become  adult  the  sexual  organs 
have  scarcely  more  than  begun  to  develop,  and  they  require  a  great  deal 
of  food  for  this  purpose.  Those  whose  sexual  organs  had  developed 
considerably  in  the  fall  were  not  able  to  survive  the  winter  because  of 
that  drain  on  their  vitality,  and  only  those  in  which  these  organs  were 
not  growing,  are  alive  in  the  spring.  These  organs  with  the  return  of 
warm  weather  start  to  grow,  and  as  this  sharpens  the  appetite  of  the 
insects,  they  become  more  restless  and  migratory.  As  soon  as  the 
grape-vines  leaf  out,  they  will  find  the  hoppers  waiting  for  them. 


How  they  feed.  By  carefully  examining  the  under  side  of  the  body 
with  a  microscope,  one  will  notice  between  the  six  legs  lying  on  the 
breast  and  projecting  backward  from  the  head,  a  rather  thick  pointed 
organ  which  is  capable  of  being  bent  out  nearly  at  right  angles  from  the 
body.  This  is  the  proboscis  or  sucking-tube  by  means  of  which  the 
insect  obtains  its  food.  The  method  of  inserting  it  can  be  observed 
by  lying  down  under  a  vine  and  remaining  quiet  a  little  while  till  the 
hoppers  get  accustomed  to  your  presence,  when  by  watching  an  insect 
that  has  alighted  in  such  a  position  that  one  gets  a  side  view  of  it,  he 
may  see  the  whole  process.  The  insect  first,  by  straightening  its  legs, 
raises  itself  from  the  plant  a  distance  about  equal  to  the  length  of  its 
proboscis.  The  proboscis  will  then  be  seen  to  bend  down  till  the  tip 
touches  the  plant  and  then  the  insect  draws  itself  towards  the  leaf,  forc- 
ing the  proboscis  in  its  full  depth.  The  insect  comes  thus  much  closer 
to  the  leaf  than  it  would  ordinarily  stand.  The  food  is  sucked  up 
through  the  proboscis,  and  includes  not  only  the  juices  of  the  plant, 
but  also  the  more  solid  substances  in  the  cavities  of  the  leaf,  the  pale 
spots  being  due  to  the  removal  of  the  green  bodies  of  the  leaf. 

The  injury  to  the  pla?its.  Whereever  the  beak  is  inserted  the  skin  or 
cuticle  of  the  leaf,  which  protects  the  leaf  from  drying  out,  is  broken 
and  the  leaf  is  that  much  weakened,  or  requires  that  much  more  water 
to  keep  it  in  healthy  condition.  Some  of  the  substance  of  the  leaf  is 
also  removed  and  the  leaf  has  less  of  the  green  bodies  which  are  essen- 
tial in  the  manufacture  of  the  food  for  the  growth  of  the  plant,  but  these 
are  not  as  important  as  the  loss  of  water  and  the  inj  ury  to  the  cuticle 
which  makes  a  continual  leakage.  The  injury  from  loss  of  water  is 
twofold  ;  first,  the  only  condition  under  which  growth  is  possible,  is 
that  the  water  in  the  growing  part  be  under  tension,  that  is,  that  it  be 
supplied  faster  than  it  is  used,  and  if  the  leakage  prevents  this  tension, 
no  growth  can  take  place  no  matter  how  much  food  may  be  present. 
Secondly,  when  the  tension  is  removed  the  leaf  undergoes  changes 
which  we  call  ripening,  which  finally  result  in  the  death  and  dropping 
of  the  leaf.  Now  every  leaf  costs  the  plant  something  in  its  production. 
The  leaf  is  a  factory  for  food,  and  unless  it  remains  on  the  plant  long 
enough  to  manufacture  more  than  it  costs  it  is  a  loss  to  the  plant.  The 
leaf  hopper  is  a  very  small  insect,  and  it  would  require  a  great  number 
to  be  as  much  of  a  drain  on  the  vine  as  the  production  of  a  berry  if, 
like  the  fruit,  they  merely  took  their  food  from  the  plant  without  other- 
wise injuring  it.  But  the  hopper,  while  taking  nowhere  near  as  much 
food  from  the  plant  as  the  fruit  does,  still  is  able  to  stop  the  growth  and 
kill  the  leaves.  It  will  be  seen  that  this  injury  is  produced  only  when  the 
loss  of  water  is  large  enough  to  seriously  reduce  the  tension.  In  the 
drier  regions  and  in  the  drier  part  of  the  year,  therefore,  the  injury  is 
most  severe.     Under  favorable  conditions  it  might  amount  to  nothing. 

There  is  a  special  condition  in  the  spring  of  the  year,  when  an  injury 
occurs  of  a  somewhat  different  nature.  Usually  the  hoppers  do  not  at- 
tack seriously  the  very  young  leaves,  but  in  the  spring,  if  the  vines 
come  out  late  or  the  insects  are  in  unusual  numbers,  or  if  the  weather 


— 7— 

is  warm,  favoring  their  early  and  active  migration  to  the  vines  (all  of 
which  conditions  occurred  this  spring),  the  hoppers  may  attack  the  ex- 
panding leaves  and  so  injure  them,  especially  at  the  veins,  that  they 
never  fully  expand ;  and  the  leaves  ripen  very  fast  and  fall  before  they 
are  hardly  replaced  by  new  foliage.  In  the  meantime  the  first  fruit 
buds  appear  and,  because  of  this  condition  of  affairs,  fail  to  set  fruit. 
This  occurs  only  early  in  the  spring  and  not  very  commonly  with  this 
species,  but  more  often  in  the  case  of  the  large  leaf  hopper  that  is  found 
along  the  coast. 

Egg -laying.  The  eggs  begin  to  be  laid  by  the  time  the  first  buds 
appear  and  are  laid  continuously  all  the  rest  of  the  season.  At  the  end 
of  the  abdomen  of  the  female  there  is  a  spear-like  ovipositor  concealed 
between  two  large  plates,  which  form  quite  a  third  of  the  abdomen. 
This  ovipositor  is  nearly  as  long  as  the  proboscis  and  is  inserted  into  the 
plant  in  much  the  same  way  and  the  egg  is  forced  through  it  into  the 
plant.  Eggs  are  laid  only  in  the  soft  new  growth,  on  the  leaves  or 
stems  or  tendrils.  The  insects  produce  only  a  single  egg  at  a  time, 
which  is  relatively  large.  They  continue  a  long  while,  producing  them 
certainly  till  after  their  children  are  grown  and  have  begun  to  lay  eggs. 
There  seem  to  be  no  data  as  to  the  number  of  eggs  produced  nor  the 
length  of  time  it  takes  an  egg  to  hatch. 

The  young  insects.  The  young  insect  on  hatching  crawls  out  into  the 
open  air  and  making  its  way  to  the  nearest  leaf  takes  a  position  on  the 
under  side,  preferably  near  a  vein,  and  leads  a  very  quiet  life.  It  ob- 
tains its  food  in  the  same  way  as  the  adult  and  resembles  it  in  most  par- 
ticulars, but  is  of  course  without  wings.  Though  it  is  capable  of  jump- 
ing, it  must  be  disturbed  a  great  deal  before  it  can  be  made  to  do  so, 
preferring  to  run  away  or  to  hide  next  to  a  vein.  This  retiring  dis- 
position makes  it  a  very  inconspicuous  insect.  As  it  grows  it  goes 
through  a  set  of  moults  as  do  other  insects,  finally  obtaining  wings  as  it 
becomes  adult.  The  number  of  moults  that  the  insect  passes  through 
has  not  been  determined.  The  injury  done  by  the  insects  while  young 
does  not  seem  to  be  very  large  as  compared  with  that  done  by  the  adult. 
Their  sluggish  habits  and  shorter  life  requires  less,  as  well  as  the  fact 
that  they  have  to  provide  only  for  their  own  growth. 

THE   HOPPERS   IN   SUMMER. 

The  numbers  in  the  spring  gradually  increase  until  practically  all  the 
hoppers  have  left  the  other  plants  and  accumulated  on  the  vine  ;  then 
they  gradually  decrease  as  the  more  feeble  ones  die,  until  the  beginning 
of  summer  when  the  first  brood  of  young  ones  begin  to  reach  maturity 
and  augment  the  numbers.  This  is  about  the  first  of  June.  From  that 
time  on  they  continue  to  multiply  as  long  as  the  season  lasts,  and  at 
any  time  the  insects  can  be  found  in  all  stages  of  development. 

The  characteristic  appearance  of  the  leaf  affected  by  these  insects  now 
becomes  everywhere  apparent.  Besides  the  pale  mottlings  that  have  al- 
ready been  mentioned,  one  may  notice,  especially  on  the  under  side 
where  the  insects  chiefly  stay  when  not  on  the  wing,  many  small  spots 


— 8— 

of  all  shades  from  brown  to  black.  These  spots  are  the  excrement  of 
this  insect.  Similar  spots  are  made  by  other  insects  of  this  order  and 
by  the  true  thrips.  The  worst  affected  leaves  gradually  die  and  fall, 
making  the  vines  almost  bare  when  they  should  be  dense  with  leaves. 
When  this  condition  is  produced,  the  fruit  is  of  an  inferior  quality. 
Especially  is  it  lacking  in  sugar  and  other  solid  contents,  and  therefore 
dries  into  small  raisins,  or  makes  a  thin  watery  must  for  wine-making. 

RKMKDIKS. 

Under  this  head  we  will  treat  the  various  means  that  have  been  em- 
ployed or  suggested  for  preventing  or  mitigating  the  injury  from  leaf 
hoppers. 

Sheeping  the  vineyard.  This  is  one  of  the  favorite  remedies  and  is 
depended  on,  more  because  it  is  supposed  that  it  ought  to  work  than 
because  any  one  has  ever  had  good  results.  There  is  a  natural  varia- 
tion from  year  to  year  with  this  as  well  as  with  all  other  insects,  and  as 
one  is  most  likely  to  try  a  remedy  of  any  kind  during  or  just  after  a  bad 
season,  it  is  not  surprising  that  there  is  considerable  testimony  to  the 
effect  that  good  results  follow  sheeping.  No  one  who  has  carefully  com- 
pared adjacent  vineyards  where  sheeping  and  not  sheeping  have  been 
employed ,  will  be  able  to  say  that  there  is  an  appreciable  difference  in 
the  fields.  We  are  not  discussing  the  merits  or  demerits  of  turning 
sheep  in  the  vineyard  to  eat  off  the  leaves  ;  but  as  far  as  its  effects  in 
reducing  the  numbers  of  leaf  hoppers,  there  is  not  one  particle  of  reliable 
evidence  in  its  favor.  The  theories  for  sheeping  are  many  but  all  un- 
tennable.  Some  hope  to  destroy  the  eggs  and  young,  and  this  in  a 
measure  they  do  accomplish  ;  but  they  do  not  realize  the  fact  that,  if 
left  alone,  all  of  these  would  die  during  the  winter  ;  and  that  the  only 
ones  destined  to  pass  the  winter  are  the  adults  which  the  sheep  do  not 
destroy  but  cause  to  take  wing. 

Others  have  the  idea  that  by  feeding  the  leaves  the  insects  will  be  un- 
able to  find  a  suitable  place  to  pass  the  winter  ;  whereas  to  destroy  their 
wintering  place  it  would  be  more  effectual  to  let  the  vineyard  alone  and 
to  cause  the  sheep  to  brouse  off  all  the  citrus  and  other  evergreen  trees, 
and  all  the  grass  and  weeds  along  the  ditches, — indeed  to  make  the 
whole  country  bare  and  to  keep  it  so  all  winter.  One  would  starve  the 
sheep  to  death  before  he  would  the  bugs,  and  in  every  respect  the 
method  is  impossible  and  ridiculous.  Again  others  think  that  the  sheep 
would  crush  those  in  the  ground.  As  a  matter  of  course  there  are  none 
in  the  ground  and  there  is  no  reason  to  think  that  they  would  be  crushed 
if  they  were  there.  The  only  place  that  is  beaten  hard  by  sheep  are  the 
paths  they  follow  and  the  place  they  sleep  at  night.  A  few  may  be 
crushed  on  the  surface,  but  a  hopper  so  feeble  as  not  to  be  able  to  get 
out  of  the  way  of  the  feet  of  the  sheep  could  not  withstand  the  winter. 

Destroying  the  leaves.  Many  farmers  have  gone  to  the  trouble  of 
gathering  and  burning  the  leaves,  or  of  plowing  a  furrow  and  raking 
them  in  and  burying  them.  The  reasoning  is  about  the  same  as  those 
in  favor  of  sheeping.   Farmers  are  not  alone  in  this  matter,  forentomolo- 


gists  everywhere  have  repeatedly  advised  such  a  cleaning  up  to  destroy 
what  were,  or  what  were  supposed  to  be,  hibernating  places.  These 
recommendations  appear  in  practically  every  book  treating  on  remedies 
for  insects,  but  it  is  a  fact  that  even  in  cold  climates,  where  insects  do 
hibernate,  there  has  never  been  a  single  reliable  experiment  on  an  insect 
of  any  kind  that  substantiates  this  method's  claim  to  practical  utility. 
We  do  not  mean  that  no  experiments  have  been  tried,  but  that  not  only 
have  no  economic  results  been  produced,  but  all  results  have  been  either 
negative  or  unreliable.  In  our  climate,  with  hardly  any  true  hiberna- 
tion and  an  insect  that  does  not  hibernate,  this  method  can  only  be 
futile  of  results. 

Plowing-  and  rolling.  This  can  only  be  done  in  the  winter,  after 
pruning,  or  in  the  spring,  before  the  growth  is  far  advanced.  By  the 
time  the  pruning  is  through  with  there  will  be  very  few  of  the  hoppers 
in  the  vineyard  that  are  vigorous  enough  to  get  away,  and  it  is  doubt- 
ful if  those  that  still  remain  include  many  that  would  be  likely  to  pass 
the  winter  successfully.  The  general  idea  of  winter  plowing  and  roll- 
ing is  based  on  the  supposition  that  the  insects  are  in  the  ground  and 
could  be  reached  by  such  methods.  In  the  spring,  after  the  hoppers 
have  attacked  the  vines,  it  is  the  practice  of  some  to  jar  the  insects  onto 
the  ground  in  the  morning,  when  they  will  not  attempt  to  return  to  the 
vine,  and  turn  them  in  with  plow,  disk,  or  cultivator,  or  harrow  and 
sometimes  follow  with  a  crusher  or  roller  ;  and  there  is  no  doubt  that 
in  this  way  some  of  the  insects,  perhaps  quite  a  good  proportion,  will 
be  destroyed.  We  do  not  think  that  the  results  attained  will  in  any 
way  justify  the  expense,  and  the  method  can  only  be  applied  during  the 
night  or  on  a  cool  morning.  Unless  the  cultivation  is  necessary  in 
itself  it  could  not  be  thought  of  as  a  remedy  for  the  hopper.  There  may 
be  opportunity  of  employing  it  economically,  however,  but  alone  it  can 
never  be  effectual,  as  it  can  only  be  used  early  in  the  spring. 

Winter  spraying.  This  luxury  has  often  been  indulged  in  with  end- 
less variation  as  to  detail.  Often  the  bark  has  been  carefully  stripped 
off  the  stumps  before  the  spray  was  applied.  Almost  every  kind  of 
spray  has  been  tried  and,  of  course,  never  with  brilliant  results.  Often 
the  farmer  will  say  that  he  thinks  it  did  some  good,  but  none  think  that 
it  has  paid  for  the  trouble.  The  fact  is  that  it  had  no  effect  whatever 
on  the  hoppers,  and  as  far  as  the  hopper  is  concerned,  all  the  money 

spent  in  this  way  is  wasted. 

Summer  spraying.  While  winter  spraying  is  the  most  useless  thing 
that  can  be  done,  spraying  in  the  summer,  when  there  is  something  in 
the  vines  to  kill,  is  an  effectual  process.  All  that  can  be  said  against  it 
is  the  difficulty  and  cost.  Indeed  this  is  so  great  that  it  is  doubtful  if 
it  is  really  practicable.  There  is  a  great  difference  between  effective- 
ness and  practicability.  Nothing  is  practical  unless  it  pays.  When  it 
is  said  that  spraying  is  effectual,  the  statement  should  be  modified  to 
this  extent.  The  insect  is  so  active  that  it  is  impossible  to  prevent 
many  from  escaping,  and  they  are  so  difficult  to  wet  that  it  is  necessary 
to  use  a  very  strong  and  penetrating  wash  like  the  kerosene  emulsion, 
to  get  even  fair  results.     In  the  spring  it  is  quite  easy  to  spray,  as  the 


—  IO — 

material  used  can  be  taken  through  the  fields  on  a  truck,  but  as  soon 
as  the  vines  cover  the  ground  it  becomes  another  matter.  Then  the  use 
of  knapsack  sprayers  seems  to  be  the  only  way  to  apply  a  spray.  The 
necessity  of  spraying  from  below  increases  the  difficulty  and  expense  of 
such  a  treatment.  The  only  spray  that  does  any  good  is  one  that  will 
kill.  It  is  not  possible,  for  instance,  to  make  the  vines  distasteful  to  the 
hopper  and  so  make  it  starve  to  death.  Many  things  have  been  tried 
for  this  purpose,  but  nothing  has  ever  been,  and  probably  never  will  be, 
found  to  do  it  with  this  insect  or  any  other. 

Jarring.  Jarring  is  one  of  the  commonest  remedies  tried  in  the  spring 
and  under  some  conditions  it  is  one  of  the  best.     The  sketch,  Fig.  i, 


Fig.  i. 


given  herewith,  is  one  that  has  been  used  in  Europe  for  a  different  kind 
of  insect,  and  has  been  recommended  by  European  authors  for  their 
vine  hopper,  which  is  related  to  our  insect,  but  has  never  been  abund- 
ant enough  to  really  need  a  remedy.  It  consists  of  a  tin  funnel  with  a 
notch  to  enable  it  to  be  held  under  a  vine  and  a  cloth  bag  tied  to  the 
bottom  to  hold  the  hoppers.     In  the  next  sketch,  Fig.  2,  is  shown  a 


Fig.  2. 

modification  which  differs  in  the  addition  of  a  conical  tin  handle,  in 
which  may  be  inserted  a  short  stick  if  it  is  desired  to  increase  its  length. 
About  a  foot  and  a  half  in  diameter  will  be  found  a  convenient  size. 
Any  tinner  can  readily  make  the  funnel. 


II 


In  the  work  in  this  State  the  favorite  form  has  been  something  like  a 
large  scoop.  It  is  generally  made  broad  with  a  notch  in  the  edge,  and 
one  held  on  each  side  of  the  vine  while  it  is  jarred,  and  the  insects  that 
fall  on  the  scoop  are,  from  time  to  time  as  they  accumulate,  poured  into 
a  vessel  containing  water  and  a  little  kerosene.  The  accompanying 
sketch,  Fig.   3,  gives  a  style  of  these  scoops  made  of  a  single  piece  of 


Fig-  3- 

tin.  A  part  of  one  edge  is  so  bent  as  to  fit  a  handle.  The  corners  are 
rounded  and  a  notch  is  made  in  the  edge  opposite  the  handle.  Two 
men  proceed  up  a  row  of  vines  placing  the  scoops  below  the  vine  and 
one  of  them  jars  the  vine  with  a  stick. 

The  success  of  jarring  will  depend  on  preventing  the  hoppers  escap- 
ing from  the  scoops  and  can  only  be  used  when  the  hoppers  will  fall 
well.  It  likewise  cannot  be  used  after  the  vines  attain  considerable  size: 
therefore  this  method  alone  cannot  be  depended  on,  however  well  it  may 
work  in  the  spring. 

The  hopper  dozer.  Great  ingenuity  has  been  displayed  in  the  design- 
ing of  hopper  dozers.  By  this  term  is  meant  any  contrivance  against 
which  the  insect  may  be  made  to  leap  or  fall  and  which  will  cause  their 
death.  Generally  they  are  coated  with  a  sticky  substance  on  the  prin- 
ciple of  a  fly  paper.  Many  have  been  made  on  the  principle  of  the 
scoops  for  jarring,  but  where  tried  have  generally  been  replaced  by  the 
scoop  without  the  sticking  mixture.  Others  which  work  very  well  have 
been  shaped  like  a  bell  jar ;  this  kind  can  only  be  used  during  the  hotter 
part  of  still  days,  while  the  insects  fly  well.  Both  of  these  forms  are 
only  intended  for  use  in  the  spring  while  the  vines  are  small,  and  the 
latter  only  on  short-pruned  varieties.  They  both  are  troublesome  to 
recharge  with  the  sticking  mixture  and  probably  have  been  discarded 
in  every  case  after  the  first  trial. 

There  is  another  form  that  has  been  used  successfully  in  the  eastern 
States  on  a  small  scale,  and  which  promises  to  be  much  more  satisfactory 
for  use  here  than  any  kind  as  yet  tried  in  the  State.  It  consists  simply  in 
a  plain  palm-leaf  fan.  The  idea  is  to  have  a  can  of  the  sticking  mixture 
large  enough  to  dip  the  fan  into,  and  arming  each  man  with  a  stick  with 
which  to  jar  the  vines,  and  a  fan  to  catch  the  insects  with,  have  them 
go  rapidly  through  the  vineyard,  from  vine  to  vine.  In  the  morning 
while  they  drop,  it  may  be  well  to  work  the  men  in  pairs  thus  :     Give 


12  — 


one  man  two  fans  and  the  other  a  fan  and  a  stick.  When  they  come  to 
a  vine  the  three  fans  will  be  held  below  the  vine,  touching  the  trunk 
and  overlapping  each  other.  The  vine  is  then  jarred  and  the  insects 
caught.  As  the  day  gets  warmer  and  some  of  the  insects  fly,  those 
that  drop  are  first  caught  and  then  the  fans  at  once  swung  catching 
those  in  the  air.  After  they  cease  to  drop  the  men  can  work  independ- 
ently, though  even  then  it  may  be  well  to  continue  to  work  in  pairs. 
The  sticking  mixture  may  be  kept  at  the  end  of  the  rows.  This  method 
is  applicable  all  summer,  but  even  this  can  only  be  used  for  hoppers  on 
the  wing  after  the  vines  are  large. 

The  net.  The  use  of  the  insect  net  has  not  been  seriously  thought  of  as 
a  means  of  combatting  this  insect  on  a  large  scale  until  this  year,  as  far 
as  we  are  aware.  Experiments  seem  to  indicate  that  it  will  prove  thor- 
oughly practical.  The  form  of  net  that  we  prefer  is  made  as  follows : 
For  a  net  a  foot  in  diameter  take  a  piece  of  wire  forty  inches  long,  bend 
about  an  inch  and  a  half  of  each  end  at  right  angle,  and  then  bend  the 
whole  wire  into  a  hoop  bringing  the  bent  ends  parallel.  Make  a  tin  fer- 
rule about  six  inches  long,  increasing  from  one  quarter  to  about  three 
quarters  of  an  inch  in  diameter  at  the  larger  end.  Solder  the  ends  of  the 
hoop  into  the  smaller  end  and  the  hoop  is  complete.  The  ferrule  serves 
as  a  handle,  or  when  a  longer  handle  is  needed  a  stick  may  be  inserted 
into  it.  The  bag  of  the  net  is  made  of  a  yard  of  cheese  cloth.  Fold 
the  cloth  so  as  to  bring  the  selvages  of  one  side  together  and  sew  along 
the  selvage.  This  will  make  a  conical  bag.  Now  trim  the  cloth  so  that 
the  edge  is  everywhere  a  half  a  yard  from  the  point  of  the  bag.  Gather 
the  edge  of  the  bag  on  the  hoop,  making  a  hem,  and  the  net  is  com- 
plete.    [Fig.  4.]     A  net,  having  a  diameter  of  a  foot  and  a  half  may 


Fig.  4. 


be  found  more  useful,  in  which  case  a  wire  about  sixty  inches  long,  and 
four  feet  of  cheese  cloth,  will  be  needed,  but  otherwise  it  is  made  in  the 
same  way. 


—13— 

In  using  the  net  one  first  jars  the  vine  and,  as  the  insects  fly,  a  few 
strokes  with  the  net  will  catch  the  great  majority  of  them,  if  skillfully 
done.  With  a  net  of  this  shape  the  insects  will  all  accumulate  in  the 
tip  and  can  be  quickly  crushed  to  death  with  the  hand  or  emptied  into 
water  and  kerosene  if  desired.  The  practicability  of  the  method  will 
depend  on  the  skill  of  the  workmen,  but  the  skill  is  easily  acquired  and 
most  every  one  will  get  the  idea  at  once.  The  nets  could  be  used  early 
in  the  morning  in  the  same  way  suggested  in  the  case  of  the  fan  hopper 
dozer.  The  net  is  equally  as  rapid  as  the  fan,  does  not  require  the 
sticking  mixture  and  is  therefore  preferable  ;  though  it  may  require 
more  skill  in  handling  and  therefore  with  some  men  be  less  satisfac- 
tory. Like  the  fan  method  the  net  may  be  used  all  summer.  The  two 
comprise  the  only  methods  (with  the  possible  exception  of  spraying) 
which  are  at  all  practical  for  summer  use,  at  least  with  the  Californian 
methods  of  culture. 


TREATMENT. 

We  have  thus  far  considered  the  remedies  available  for  treating  the 
vine  hopper  ;  there  yet  remains  to  be  discussed  the  theories  and  program 
of  treatment.  Almost  every  kind  of  remedy  that  has  been  suggested 
for  destroying  insects,  has  been  tried  for  the  leaf  hopper  without  suffi- 
cient success  to  justify  its  continuance,  and  either  we  must  wait  for 
some  brilliant  discovery  and  in  the  meantime  allow  the  insect  to  be  un- 
controllable, or  we  must  radically  change  our  theory  of  treatment.  In 
all  the  experiments  in  this  State  the  idea  has  been  to  destroy  the  insect 
in  the  winter  or  spring  and  to  depend  on  that  for  the  protection  of  the 
crop  through  the  rest  of  the  year.  The  desire  has  been  to  exterminate 
the  insects  or  approach  that  result  as  nearly  as  possible  ;  but  that  has 
proven  impracticable.  It  seems  about  time  to  stop  the  war  of  extermi- 
nation and  turn  our  attention  to  another  solution  of  the  problem  which 
gives  more  reason  to  hope  for  success. 

The  new  theory  of  treatment  that  is  proposed  is  based  on  the  fact  ob- 
served by  all  that  a  small,  or  even  a  considerable  number  of  hoppers 
does  not  appreciably  injure  the  crop.  Of  this  fact  every  grower  in  the 
State  can  bear  witness  Good  crops  can  be  produced  in  spite  of  the 
hoppers,  and  it  is  only  their  excessive  numbers  that  are  injurious.  The 
problem  can  be  reduced  then  to  this  question  :  Is  it  possible  to  reduce 
the  numbers  in  a  field  below  the  danger  mark  ?  It  must  be  possible  to 
do  so  at  any  time  and  at  a  small  expense.  The  question  then  arises  : 
What  is  the  danger  point?  This  cannot  be  definitely  answered,  but 
observations  during  years  when  there  is  the  greatest  loss  and  during 
those  in  which  the  loss  is  trifling  leads  us  to  believe  that  if  the  number 
could  be  reduced  fifty  per  cent,  in  the  worst  years,  the  injury  would  be 
avoided.  If  it  is  true  that  such  a  reduction  would  prevent  the  injury, 
the  question  is,  Can  fifty  per  cent,  of  the  insects  be  cheaply  destroyed? 

According  to  the  best  estimate  we  could  make  by  actual  trial  in  the 
field,  of  the  effect  of  the  use  of  the  net  in  the  spring,  it  appeared  that 


— 14— 

a  much  larger  percentage  than  that  could  be  destroyed  —  nearer  ninety 
per  cent. ,  and  this  too  while  working  at  a  rate  of  about  five  acres  a  day. 
About  half  of  a  gang  of  men  green  hands  at  the  business,  part  white 
and  part  Chinese,  did  almost  as  well  as  one  skilled  with  the  net.  At 
the  rate  of  wages  they  were  getting,  the  cost  per  acre  would  be  between 
fifteen  and  twenty  cents.  This  makes  it  a  wonderfully  cheap  process. 
If  it  cost  twice  as  much  and  had  to  be  done  a  dozen  times  in  a  year,  it 
would  not  begin  to  cost  as  much  as  the  loss  to  a  crop  in  a  bad  year. 
It  seems  to  have  been  proven  by  actual  test  that  a  good  percentage  of 
the  hoppers  can  be  taken  and  killed  by  the  use  of  the  net  and  at  a  cost 
per  acre  that  is  nominal.  There  yet  remains  to  be  seen  whether  the 
vineyardist  can  develop  a  judgment  that  is  to  be  depended  on  as  to  when 
the  insects  are  approaching  the  danger  point,  and  to  set  the  nets  going. 
According  to  this  new  theory  of  treatment  it  would  appear  that  we 
have  the  true  solution  of  the  problem  and  that  the  net  or  the  palm-leaf 
fan  are  the  means  giving  the  greatest  promise. 


L0UI6  ROESCH  CO.,  PRINTERS,  8.  F. 


